"There are no second acts in American lives," F. Scott Fitzgerald once lamented.
As an admirer of the American political scene - he idolises Robert F Kennedy and his "strain of moral commitment" - Gordon Brown could have been forgiven for assuming his defeat at the 2010 general election would similarly curtail his political career.
But politics has a way of surprising even the veteran and practised. The election of an SNP majority government at Holyrood in 2011 made a referendum on independence inevitable. Mr Brown's role in the campaign was muted at first but in the final months, with the Yes vote creeping up in poll after poll, he was called upon to lend his integrity to a campaign that had alienated Labour voters with its negativity.
The mythology surrounding The Vow has long since loosed itself from the text of that pledge and those Nationalists who at the time of its publication dismissed it as a stunt not to be taken seriously now speak of it in reverent tones, as though Mr Brown had followed Moses down Mount Sinai with a scroll of revisions.
Where Brown really came into his own was not in a few lines on the front page of the Daily Record. His speech on the eve of referendum day was one of the most impassioned perorations any of us will see in our lifetimes. Every word burned with righteous fury. Gone were the standard punctuation marks of public speaking: The tempered pace, the modulations of tone, and the pauses deployed for solemn effect. There was no time for such niceties; there was a country to be saved.
Scotland voted No and the voters waited to see if Brown's promise of "nothing less than a modern form of Scottish home rule" would come to pass. The Smith Commission, which reported last week, contained a substantial range of powers but if it represents a modern form of home rule, it is a modern one indeed. This is why Mr Brown has been the target of so much ire from the Nationalists. They perceive him to have scuppered their chances of independence then reneged on his pledge to the voters.
The truth is somewhat more nuanced. Mr Brown's grandiloquent pronouncements were the words of a maverick let off the leash. He was in no position to deliver these promises but with the Union at stake, the No campaign allowed itself to forget such practicalities and sighed with relief as the popular former Labour leader roused the faithful. Whether he saved the UK, we will never know. However, we can say with certainty that his contribution was large and substantial and came at a time of crisis in Better Together.
Of course, we're beginning at the end. Mr Brown stepped onto the political stage in 1983, at Labour's lowest ebb. Some questioned at that time, not unreasonably, whether Labour would survive the decade. Mr Brown joined the vanguard of bright young things, at first surrounding Neil Kinnock and then running the party themselves, who dragged Labour out of electoral irrelevance and refashioned it into an election-winning machine, an outfit which Tony Blair aptly nominated the "political wing of the British people".
That ambition was realised in the 1997 landslide, which didn't so much redraw the map of British politics as take giant tin of red paint and pour it over every part of the UK. The election ushered in a new, reforming government and Brown kickstarted the changes by devolving control over interest rates to the Bank of England. This wasn't your father's Labour Party.
As Chancellor of the Exchequer, Mr Brown set about creating new taxes and redistributing wealth by stealth, targeting Britain's social and economic travails while keeping the City and the Daily Mail (more or less) on board. There was a national minimum wage, sustained economic growth, and the canny Scot's prudence kept the UK out of the euro.
But Mr Brown's flaws -- political, economic, and personal -- were many and came to overshadow his successes. He was a control freak; like all geniuses, frustrated at the mediocrity of those around him. He was intemperate of alternative points of view and disdainful of collective decision-making. The sketchwriters' caricature of a dour, brooding Scot set English public opinion against him and every attempt to win it over ended badly, and often embarrassingly.
He flunked the courage test when he failed to call an election in 2007 and secure a mandate for his government. His raid on pensions has still not been forgiven by those who lost out. His deregulation of the financial markets, the relaxed attitude to casino mortgages, and explosion in public expenditure all caught up with him in the credit crunch and the recession that followed. And his tribal brand of Labourism made a coalition with the Liberal Democrats impossible after the 2010 election.
The description of him by one senior Labour figure as "psychologically flawed" was a cruel jibe but one that seemed plausible, even to those who bore him no particular ill will. He was a difficult personality, forever on the shortest of fuses. The jock-baiting of some sections of the London-based press was matched by a contempt amongst journalists north of the border. Brown never swayed the commentariat the way Blair did. His problem was that he cared and, like John Major before him, it got under his skin. Few senior politicians in living memory have seemed so consistently angry.
It is obvious to cast Brown as a latter-day Macbeth, pining darkly for an office which was his eventual undoing. But the heights of his achievements and the depths of his reversals cannot help but summon the cruelest ironies of Shakepearean hamartia. Had he remained in the post which he felt smothered his larger talents, he might have been remembered as a landmark Chancellor rather than a failed Prime Minister.
When we weigh the costs and benefits in the political balance sheet, there is a missing debt on the ledger. That is the Gordon Brown no one talks about. Under Brown, Labour passed the Equality Act, a progressive piece of anti-discrimination legislation. Paid holiday leave entitlements were increased, tax credits expanded, and parents given the right to request flexible working hours. When Labour came to power in 1997, one in every four children lived in relative poverty; when Brown left office in 2010, that figure had fallen to one in five.
Brown supported the overthrow of Saddam Hussein but he was also the Prime Minister who set up the Chilcot Inquiry into the lead-up to military action. He was a champion for Africa, the kind that sent money instead of wearing sloganeering wristbands. When he entered Number Ten, the department of international development aid programme budget was just over £5bn. By the time he left, it had risen to more than £7.5bn.
And he endured every parent's nightmare when his baby daughter Jennifer Jane died aged just ten days. Some fathers could not have endured another day of public life; they would have preferred a private and sombre existence. But Brown's zeal for fighting poverty and strengthening society gave him a purpose and the drive to pursue it.
British prime ministers have tended to be realists rather than moralists and even the most patrician have shied away from invoking a higher purpose, or, Heaven forfend, a higher power in their ministry of the nation. This tradition was broken in different ways by the two great post-war prime ministers: Clement Attlee, who strove to build a New Jerusalem, and free-market evangelist Margaret Thatcher, in whose political theology the economic flaws of socialism were as nothing compared to its moral turpitude.
Amongst the generation of politicians who followed in the wake of '45 and '79, the two bitterest rivals both brought a moral impulse to bear on the business of government, though two very different strains of moralism. Tony Blair, despite the insistence of his spin doctor Alastair Campbell that "we don't do God", could often sound like an American president in his openness about his faith and the part it played in his governing philosophy. Blair's was an Anglo-Catholic ethos that thought and acted big. New Labour, New Testament.
Brown was more Old Testament. Greed and selfishness, and the structural injustices which calcify because of them, were man's original sin. Moral improvement channelled through the instrument of government could be our deliverance.
He has a mutual admiration for the conservative historian of Victorian virtue Gertrude Himmelfarb, for whose The Roads to Modernity he penned a foreword. Mr Brown told readers of Professor Himmelfarb's veneration of the British and American Enlightenments -- the ordered liberty and social commonalities of these two movements held in contrast to the radical and disruptive forces of the French Englightenment -- that Britain's contribution to modernity was "a desire to bring about a more decent, humane and compassionate society. Its temper was progressive and reformist; its proponents were social reformers and religious dissenters as well as academics and public intellectuals; and it celebrated the virtues and affections of ordinary people."
Mr Brown proclaimed his comity with this cause, "progressive change resting on a deep moral sense... individual liberty hand in hand with social responsibility and active citizenship." Left-wing intellectuals in the UK recoiled in horror at Brown's seeming endorsement of what were once reformist principles but which have since been spurned as the moralism of bourgeois meddlers and judgemental Bible-clutchers.
In this myopia, the Left was lost for the words to describe Mr Brown, who had no helpful "illegal" war or close friendship with George W Bush to define him. The truth is that Mr Brown was never a socialist in the Marxist sense. He has always been a moral romantic, an impassioned ethicist of the human condition and prosthelytiser for the redemptive power of social bonds to heal fractured individualism. A sincere Christian and a devout democrat, his is a Son of the Manse socialism. In the Book of Brown, man is fallen but together men can get back up again.
"A just balance and scales are the Lord's," Proverbs tells us. "All the weights in the bag are His work." In his farewell speech to colleagues and party workers on Monday night, Mr Brown remarked on the odd experience of reading his political obituaries before he had formally announced his resignation. Whether his flaws will come to outweigh his contributions will be debated by his partisans and his detractors. Historians, the scholarly revisers of received wisdom, will come in time to pass their judgement.
He fought a good fight, finished his course, and kept the faith. Mr Brown got his second act and in his continuing work on international development, global education, and girls' rights, he may even find a third.